How to tell what the size of an image is after removing seams in using OpenCV2 in Python?

I am trying to write some code to manipulate the individual images, "frames", from a live video from the webcam in Python using OpenCV2. I am able to manipulate the frames but I have this excess bit of the image along the edges.

Frame:

I would like the "black areas" to not be in frame so I am wondering how to manipulate the size of the canvas to allow the black areas to not be visible.

What I would like the frame to look like:

Does anyone know what code I could use to crop the canvas size?

from Recent Questions - Stack Overflow https://ift.tt/2TuWjV9
https://ift.tt/35JrEZW